DH Instruments ADCS-601 Operation And Maintenance Manual Download

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ADCS-601™ OPERATION AND MAINTENANCE MANUAL

Page 62

4.2.3

CHANGING MEASUREMENT MODE (ABSOLUTE, GAUGE)

There is a well defined order of operation for transitioning the ADCS-601 system between
measurement modes. The order is controlled by the ADCS Tools software. Mode
transitions should only be performed under ADCS Tools control. Vacuum pumps must
always be left ON in absolute mode. Before turning OFF vacuum pumps or disconnecting
vacuum supplies, transition to gauge mode.

The current ADCS-601 measurement mode is indicated by:

- <a> (absolute) or <g> (gauge> following the pressure unit of measure in the ADCS
Control Panel <Pressure> field (see Section 4.3.5.1).
- The color of the pressure standard reference pressure circuit and PG7601 bell jar in the
ADCS System Display. light blue = gauge mode (atmospheric reference), black = absolute
mode (vacuum reference) (see Section 4.3.5.2).
- The value displayed in the ADCS Run Screen Control Panel <Reference Vacuum> field.
<N/A>= gauge mode; numerical value = absolute mode (see Section 4.3.5.1).

The complete ADCS-601 system is always in either absolute or gauge measurement mode.
Target pressure requests are interpreted and set in the active measurement mode. In
absolute mode the ADCS-601 pressure standard reference pressure circuit is pulled down to
vacuum by the reference vacuum system. In gauge mode, the reference pressure circuit is
open to atmospheric pressure.

To change the ADCS-601 measurement mode from gauge to absolute or absolute to gauge,

press the down arrow next to the

[MEASUREMENT MODE]

button on the

ADCS Main Run

Screen Toolbar

(see Section 4.3.5.3). The

ADCS Main Run Screen

<Pressure>

field displays

< ---Measurement Mode Transition--- >

while the ADCS-601 system makes the changes

necessary to change measurement modes. Do not attempt any other operations until the
measurement mode transition is complete, as indicated by the

<Pressure>

field no longer

indicating

< ---Measurement Mode Transition--- >

and the

Status Bar

(see Section 4.3.4) no

longer indicating transition activities. This process may require several minutes to complete.

After a measurement mode change, the ADCS pressure (pressure on

TEST(+)

port) is

always vented to atmosphere.

Pressing the

[MEASUREMENT MODE]

button itself, rather than the down arrow next to it, is

used to reset the current measurement mode.

4.2.4

SETTING PRESSURES

Before setting a pressure, be sure that the TEST(+) port is not open to atmosphere or
connected to a system with a very large leak. Execution of certain pressure requests could
damage the ADCS-601 system if the TEST(+) port is open. If nothing is connected to the
TEST(+) port, it must be plugged with the plug quick connect stem provided.

To set a pressure with ADCS-601, first verify that ADCS-601 is in the desired measurement
mode (gauge or absolute) (see Section 4.2.3) and that the

TEST(+)

port is not open to

atmosphere. If nothing is connected to the

TEST(+)

port, it should be plugged with the plug

quick connector stem provided.

Enter the desired target pressure in the

ADCS Control Panel

<Target Pressure>

field and

press